Data networks are employed to transmit messages and data from a network appliance which initiates a network event, such as a query or a data transfer, subsequently also referred to as an initiator, application, server or host, to another network appliance which can respond to the event, for example, a data storage device. In various types of networks, for example in Storage Area Networks (SAN), defined access paths between the network appliances, may have to conform to an access path policy. The defined access paths are physical and logical pathways, which can include the initiators, their particular components and ports, such as Host Bus Adapters (HBA), a switch fabric with switches, routers and the like, and end devices, such as physical storage devices, containing Logical Unit Numbers (LUN). The state of each of the components has to be properly logically configured to enable appropriate flow along the pathway. In addition, the physical pathways typically have to comply with a policy, also referred to as access path policy, which includes policy attributes, such as path redundancy, path connectivity characteristics, and the like.
One example of a data network with defined logical access path is a storage area network which enables multiple applications on servers access to data stored in consolidated, shared storage infrastructures. Enterprises increasingly deploy large-scale, complex networks to gain economies-of-scale business benefits, and are performing and planning extensive business-critical migration processes to these new environments.
Data networks are constantly undergoing changes, upgrades and expansion, which increases their complexity. The number of components and links which may be associated with the data transfer between a given initiator and one or more of its data network appliances may increase exponentially with the size of the network.
This complexity, which is compounded by the heterogeneity of the different network devices, leads to high risk and inefficiency. Changes to the network, which can happen frequently, may take a long time to complete by groups of network managers, and are error-prone. For example, in many existing enterprises a routine change, such as adding a new server to a network, may take 1-2 weeks to complete, and a high percentage (sometime 30-40%) of these change processes include at least one error. It is estimated that around 80% of enterprise outage events are a result of events related to changes in the network infrastructure.
To implement the access relationships and related access characteristics, multiple underlying devices of different types and related physical/logical access paths between these devices need to be set up. The physical and logical set-up can include multiple actions (sometime tens per a single logical change), which need to be set up at different locations and with device types, with perfect mutual consistency.
It would therefore be desirable to detect inconsistencies in the physical and logical access paths when making changes in the network, to analyze these inconsistencies and to find the root causes for the inconsistencies between the changed access path and the access path policy for the network.